/Engine/Source/Runtime/Engine/Public/Animation/AnimSubsystem_SharedLinkedAnimLayers.h
Add a class to the persistent class array, insuring one instance is kept alive even when unlinked.
void AddPersistentAnimLayerClass ( [TSubclassOf](API\Runtime\CoreUObject\Templates\TSubclassOf)< [UAnimInstance](API\Runtime\Engine\Animation\UAnimInstance) > AnimInstanceClass )